DESCRIPTION: (provided by the applicant) Tobacco use is the most preventable cause of death in this nation making innovative approaches to smoking cessation a priority. Studies of "scheduled smoking reduction" where smokers smoke only at scheduled times prior to quitting have shown significantly improved treatment outcomes. Unfortunately, little is known about why this approach enhances smoking cessation success and consequently little is known about possible ways to improve this approach. One potential mechanism concerns individual controllability of smoking intake. Basic research in behavioral pharmacology has demonstrated that manipulating the degree of controllability over drug intake may reduce the rewarding effects of drug consumption. Unfortunately, the methodology used in typical scheduled smoking studies does not allow for properly evaluating this mechanism. Basic laboratory research has employed a yoked-box or triadic design that allows for the manipulation of controllability while equating for dosing, consumption pattern, and exposure to other stimuli. The goal of this pilot study is to develop and test the feasibility of a yoking procedure to manipulate controllability over smoke intake for use with human participants in the natural environment. For this preliminary study, a single group of 40 smokers engaged in usual daily activities will be examined under conditions of ad-lib (or controllable) smoking versus yoked (or uncontrollable) smoking using a compact computerized device (personal digital assistant or PDA). Participants will first smoke as usual (i.e., ad-lib) for three days during which they record the exact timing of cigarette consumption via the PDA. In addition, acute responses to cigarette smoking (i.e., satisfaction), mood, and cigarette craving will be assessed via the PDA. Subsequently, each participant will then engage in three days of scheduled (or uncontrollable) smoking where the PDA will prompt smoking according to the exact pattern and number of cigarettes smoked during the first phase. Subjective measures will be collected in a manner identical to the first phase of the study. Such a procedure allows for equating the pattern and number of cigarettes while manipulating the degree of controllability over smoking, thereby allowing us to at least partially focus on the manipulation of control that is less confounded by other group differences. We will use CO assessments taken across each day to assess the degree to which the pattern of smoking was successfully held constant across conditions. The effect of the controllability manipulation on drug responses will be examined by comparing satisfaction from smoking across the ad-lib and scheduled conditions.